The present invention relates to the field of security systems for monitoring and controlling access to a secured or access restricted area, such as a vehicle of house, and more particularly to a multifunction system having the capability of self-diagnosing defective sensor and trigger devices and thereafter bypassing such defective equipment to allow the system to function.
Security systems are in wide use today to control and/or monitor access to secured or access-restricted areas. Such systems typically employ one or more sensors and/or trigger switches which are monitored or controlled by a central controller to sense intrusion or to allow controlled access. Examples of such systems include vehicle security systems and building security systems, which may be activated by either a remote switch or transmitter or by a key pad to enter a predetermined code. Entrance of the correct code typically arms or disarms the systems, opens or closes a door or the like.
The sensors and trigger typically detect attempts to intrude into the protected area, such as by way of a door or window, forcing a hood or trunk open, lifting or moving the vehicle or the like. The trigger devices may take the form of switches which are activated by the opening or closing of a door or window. The sensor may comprise a motion detector. To allow access through doors or other access point, devices which release or position locking elements, such as solenoid switches, are typically employed. Such sensors and trigger switches are prone to inevitable failure, particularly those elements positioned to monitor or control access to a heavily used door or access point. Such failure typically is manifested as an open circuit condition for a normally closed switch or sensor, or a closed circuit for a normally open switch or sensor.
Conventional security systems will not arm when a sensor indicates that a door or window is open, or when a sensor indicates that there is presently an intrusion into the protected area. As an example, a vehicle door left open will typically prevent the security system from being armed, or a window left open in a building will prevent the building security system from being armed. For the same reason, a defective sensor which indicates that a door is open irrespective of the position of the door, i.e., open or closed, will also prevent the security system from being armed. The result is that the vehicle or building owner is deprived completely of the benefit of the security system until the defective sensor is repaired.
Another disadvantage of conventional vehicle security systems is the fact that the audible alarm signals are typically generated by a horn or siren, and each particular system generates the same or similar alarm signals. Thus, when the vehicle is in a crowded parking lot or structure, and an alarm signal is generated, the vehicle's owner may not be able to determine whether it is his vehicle's system alarm or that of another vehicle. Further, many cities or other regulating authorities have enacted rules which restrict the maximum duration of vehicle alarm cycles to minimize noise pollution. However, such rules are not uniform, so that different maximum alarm cycle duration regulations are imposed in different parts of the country. The disparity in these regulations creates difficulties for the manufacturers of vehicle security systems who seek to distribute their products throughout the country or in other countries.
Intruders have developed certain techniques for defeating vehicle security systems. One such technique is to disconnect and reconnect the vehicle battery, seeking to disrupt power to the security system and cause the system to be reset to the disarmed mode when power is restored.
Conventional vehicle security systems are disarmed by the use of handheld transmitter encoded with the particular authorization code, by a key or by a code entered manually via a key pad. Thus, the level of security, i.e., the actions necessary to disarm the system are typically fixed. Yet there are situations in which a lower level or security, with increased convenience in the system disarming, may be acceptable, as where the car is parked in a low risk area.
One object of the present invention is to provide a security system having diagnostic capabilities for identifying defective sensor and access control elements and bypassing such defective elements to allow the system to continue to provide some measure of protection.
Another object of the present invention is to provide a security system which upon disarming provides audible signals indicating that an intrusion was attempted while the system was armed, and to provide a visual signal when the system is disarmed to identify the intrusion point.
Yet another object of the invention is to provide a security system which allows the user to program a desired alarm siren code and or to provide an audible alarm condition whose duration may be programmed by the user, so as to provide a personalized alarm signal uniquely identifying to the user that his security system is in an alarm condition, as in the case for a vehicle parked in a crowded lot or parking structure.
Another object of the invention is to provide a security system which provides audible signals indicating the arming or disarming of the system, and which signals may be selectively disabled by the user.
Still another object of the invention is to provide a security system which provides a plurality of possible security levels, in that the user may programmably select a first disarming mode wherein the system may be disarmed simply by the use a remote handheld transmitter for transmitting a user authorization code, or a second disarming mode wherein the system is disarmed by the combination of the entry of an appropriate remote transmitter code and the subsequent manual entry of an appropriate key pad code.
Other objects of the invention include the provision of a security system which interprets the removal and restoration of system power as an unauthorized intrusion event unless a predetermined switch, such as the vehicle ignition switch, is activated when power is restored.
Still further objects of the invention are to provide a multifunction programmable security system which provides power door locking and unlocking signals to lock the doors upon system arming and to unlock the doors upon system disarming, and wherein the duration of said signals is selectively variable to adapt to door lock systems of different manufacturers; and wherein the system automatically activates the vehicle interior courtesy or dome light upon system disarming for a predetermined time interval or until the ignition is turned on.
Other objects of the invention are to provide a multifunction vehicle security system which is programmably adaptable to trigger or sensor devices of either positive or negative polarity.